Constrained microlayer cellular material with high stiffness and damping

Abstract

Composite materials with high damping and high stiffness at relatively low density. These materials include three-dimensional structures of interconnected ligaments, which have multiple concentric layers alternating between stiff constraining layers and soft damping layers, so that bulk deformation of the structure results in high local shear strain and correspondingly high bulk damping.

What is claimed is: 
     
         1 . A material comprising a three-dimensional open-celled cellular structure formed by:
 forming a three-dimensional open-celled cellular template;   forming a first coating layer of a first substance on the three-dimensional template;   forming a second coating layer of a second substance on the first coating layer;   forming a third coating layer of a third substance on the second coating layer; and   removing the three-dimensional template,   the second substance being different from the first substance, and   the second substance being different from the third substance.   
     
     
         2 . The material of  claim 1 , wherein the second substance has a shear modulus
 less than one tenth the Young's modulus of the first substance, and   less than one tenth the Young's modulus of the third substance.   
     
     
         3 . The material of  claim 1 , wherein the structure comprises a plurality of hollow tubes, an outer diameter of one of the plurality of hollow tubes being more than 20 times greater than a thickness of the first coating layer. 
     
     
         4 . The material of  claim 1 , wherein the ratio of a thickness of the second coating layer to a thickness of the first coating layer is between 0.02 and 2. 
     
     
         5 . The material of  claim 1 , wherein the second substance has a damping coefficient for which tan(δ) exceeds 0.1. 
     
     
         6 . The material of  claim 1 , wherein the structure includes 1000 ligaments, wherein the ratio of the total volume of the ligaments, to the total volume of the structure, is less than 0.3. 
     
     
         7 . The material of  claim 1 , wherein the three-dimensional open-celled cellular structure is further formed by:
 forming a fourth coating layer of a fourth substance directly on the third coating layer; and   forming a fifth coating layer of a fifth substance directly on the fourth coating layer,   wherein the fourth substance has a shear modulus less than one tenth the Young's modulus of the third substance, and less than one tenth the Young's modulus of the fifth substance.   
     
     
         8 . The material of  claim 1 , wherein the second substance is composed of discrete particles. 
     
     
         9 . A structure comprising:
 a plurality of ligaments interconnected as a three-dimensional open-celled cellular structure,   each of the plurality of ligaments comprising a plurality of layers;   a first layer of the plurality of layers comprising a first substance;   the first layer being directly between
 a second layer of the plurality of layers comprising a second substance and 
 a third layer of the plurality of layers comprising a third substance, 
   the first substance having a shear modulus
 less than one tenth the Young's modulus of the second substance, and 
 less than one tenth the Young's modulus of the third substance. 
   
     
     
         10 . The structure of  claim 9 , wherein the ligaments are hollow tubes. 
     
     
         11 . The structure of  claim 10 , wherein an outer diameter of one of the hollow tubes being more than 20 times greater than a thickness of the second layer. 
     
     
         12 . The structure of  claim 9 , wherein the three-dimensional open-celled cellular structure has the structure of a micro-truss. 
     
     
         13 . The structure of  claim 9 , wherein the second substance and the third substance are the same substance. 
     
     
         14 . The structure of  claim 9 , wherein the ratio of a thickness of the first layer to a thickness of the second layer is between 0.02 and 2. 
     
     
         15 . The structure of  claim 9 , wherein the first substance has a damping coefficient for which tan(δ) exceeds 0.1. 
     
     
         16 . The structure of  claim 9 , wherein the structure includes 1000 ligaments, wherein the ratio of the total volume of the ligaments, to the total volume of the structure, is less than 0.3. 
     
     
         17 . The structure of  claim 9 , further comprising:
 a fourth layer of the plurality of layers comprising a fourth substance directly on the third layer; and   a fifth coating layer of the plurality of layers comprising a fifth substance directly on the fourth layer,   wherein the fourth substance has a shear modulus less than one tenth the Young's modulus of the third substance, and less than one tenth the Young's modulus of the fifth substance.   
     
     
         18 . The structure of  claim 9 , wherein the first substance is composed of discrete particles.